Cover interlock assembly



Aug 26, 1958 T. G. BANK 2,849,556

COVER INTERLOCK ASSEMBLY Allg 26, 1953 T. G. BANK COVER INTERLOCK ASSEMBLY 2 Sheets-Sheet 2 Filed April l, 1957 United States Patent Oiiice 2,849,556 Patented Aug. 26, 1958 COVER INTERLGCK ASSEMBLY Thor G. Bank, St. Ifaul, Minn., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis.

Application April 1, 1957, Serial No. 649,885

9 Claims. (Cl. 200-50) `This invention relates to improvements in circuit breakers and to a new and improved cover interlock for protecting the operating personnel thereof.

Circuit breakers of the enclosed type commonly utilize a front'cover which can be removed or swung open to permit inspection and maintenance by operating personnel. The live parts of circuit breakers are potentially dangerous to operating personnel. Therefore, a need was felt for an interlock which would prevent the cover from being opened until kthe circuit breaker had first been opened to deenergize these terminals. ,In addition, it was felt that such an interlock should be operable to hold the circuit breaker in an open position as long as Vthe cover .1s eff and during the time the circuit breaker Vis being removed or inserted into its enclosure.

In accordance with a preferred embodiment of the present invention, a new and improved cover interlock assembly for a circuit breaker with a removable or .Swingable cover is provided. When operating personnel wish to open or remove the circuit breaker cover, they must first lift an arm which normally protrudes through a slot in the cover and engages the cover. When this arm is raised, the circuit breaker is tripped open. Removal of the-cover allows a tension spring to bias a prop lever into position to support the arm in a raised position and hold theV circuit breaker mechanism in the Vtripped or open position.

It is therefore one object of this invention to provide a new and improved circuit breaker cover interlock which provides protection for operating personnel.

.Anotherobject of the present invention is to provide a circuit breaker ycover interlock assembly which :opens the circuit breaker mechanism before access can be had to it, and holds the .circuit breaker open while the live parts are accessible.

yAnother object lof the present invention is to provide a new and improved circuit breaker cover interlock which has fewL moving parts, is easily assembled and maintained, and is reliable under .al1 operating conditions.

.Other objects .and .advantages of the present invention will be explained `hereinafter o r will be apparent to those skilled in the art.

In the drawings:

Pig. l is a side view, with parts broken away, of a circuit breaker embodying the present invention;

Eig. 2 is a side view of .the `present invention in one position;

Fig. 3 is a sideview of thepresent invention in a second position; and

Fig. 4 is a top plan view of the structure shown in Fig. 2.

Referring more particularly to the drawings by characters o f reference, Fig. l illustrates a circuit breaker for protecting .an electric circuit (not shown), in which is incorporated a preferred embodiment of the present new and improved cover interlock assembly. Breaker 10 and its component .parts are mounted on a stationary panel 11 which supports a pair of conductive studs 13 and 14. Mounted on the extremities of studs 13 and 14 are linger contacts 16 and 17 which connect breaker 1t) in series with the power circuit controlled. Stud 13 is conductively connected to a Contact block 18 and stud 14 is conductively connected to a trip coil 19.

A spring biased current cnrrying'nger contact 21 is fulcrumly mounted on contact block 18 to cooperate with a movable Contact arm 22 pivotally mounted on a contact block 23. T rip coil 19 is electrically connected at one of its coll ends to Contact block 23 and at the other .coil end to stud ld thereby completing the series circuit through the breaker 16. This current path from stud 13 through contact block l, finger contact 21, movable contact 22, contact block 2.3, trip coil 19 and stud 14 is designated as the primary current path through the breaker 1G.

A secondary or arcing current path includes an arcing movable contact arm 24 which is pivotall'y carried by and mounted on contact arm 22 at a pivot 25. rAn arcing con-tact tip 27 of suitable material is secured to the end of arm 2d which cooperates with an a-rcing c0n tac Z3 amazed to one end of an arc runner 29. Arc runner 29 .and arcing contact 2S a-re aixed to contact block 1.8.

An overcurrent trip relay assembly is shown at 31 and described more fully in an application for U. S. patent filed by Juli-us W. Timmerman, January f7.3, 1956, Serial No. 560,497. Trip coil i9 is shown serially connected with the power circuit controlled. The trip relay 3l comprises a magnet-izable core 32 with trip coil 19 mounted thereon and magnetically coupled therewith. An armature 33 forming a Vpart of relay 31 is pivotally carF ried by core 32 at pivot 34 and is responsive to electrical Changes, either current or voltage, in the power circuit controlled. The armature 33 is limited in its open posi tion by a stop pin 36 carried by breaker 10, and is biased against stop pin 36 by a spring 37.

Armature 53 has mounted thereon an adjustable screw tripping hammer 38 which initiates operation of the breaker opening mechanism. This tripping mechanism includes va first trip block 41 which is mounted on a trip shaft 42. journaled in breaker 10. Operation of the breaker vopening mechanism is the same from this point as the -oper-ation initiated by raising the interlock assern bly, described below.

A manual reclosing mechanism is shown at 45. This reclosing mechanism is shown and described in an application for U. S. patent, tiled by Julius W. Timmerman, January 2,3, 1956, Serial No. 560,497.

In accordance with the present invention a new and improved cover interlock assembly is provided. This cover interlock assembly includes a support plate 5l mounted on back panel l1, and an interlock arm 52 nivotally mounted on support plate 51 at pivot point Si). When Athe cover 53 is in place, arm 5,2 and its handle 54 extend through aperture 56 in the cover 53. Mounted on arm 52 is a ledge 57' and mounted on ledge 57 is a screw stop 53. Y

Also Comprising a part of the present invention. are means for latching interlock arm 52 in the raised position to thereby hold the circuit breaker contacts open. A prop lever 6l is pivotally attached to interlock arm 52 at pivot point 62. Tension spring 63 is mounted between pin 66 on support plate 51 andpin 67 mounted on the prop lever 61. .Raising the arm 52 to allow the cover 53 to Vbe removed allows tension spring 63 to bias the prop 'lever 6i into an upright position and support interlock arm 52 in its raised position.

A cover pin (not shown in Fig. l) kconnected to the inner side of cover 53 is shown in Figs. 2, 3 and 4 as reference character 5S, and its function described below.

Operation of the new and improved cover interlock assembly as applied to the circuit breaker stiucture shown (J3 in Fig. 1 is as follows. Before the cover 53 can be removed or swung open, interlock arm 52 must be raised. Raising interlock arm 52 biases screw stop 58 against first trip block 41, causing a positive clockwise rotation of first trip block 41. Movement of first trip block 41 is conveycd by shaft 42 to second trip block 43, trip Iblocks 41 and 43 being ixedly attached to shaft 42.

The clockwise rotation of second trip block 43 causes roller 71 of one leg 72 of star wheel 73 to transmit a counterclockwise rotation to star wheel 73. As star wheel 73 rotates counterclockwise, roller 74 mounted on arm 77 of rocker 78 (which in the contact closed position engages endwise leg 76 of star wheel 73) drops from endwise engagment therewith. Rocker 78 is thereby freed for counterclockwise rotation about its pivot 79. The roller mounted on one end of operating arm 82 transmits the forces of tension springs 83 and breaker contact compression springs 86 and 87 against outer surface 88 of rocker 78 and further causes a positive counterclockwise rotation of rocker 78.

The roller mounted on operating arm 82 becomes disengaged from outer surface 88, thus permitting pin 89 carried by one end of operating arm 82 to follow slot 91 in cam plate 92. The movement of the lower end of operating arm 82 permits operating arm 82 to pivot about the center point 93. Trip latch 94 has its latched cam surface 96 released from the trip pin 97, also freeing trip latch bar 98. The trip latch bar 98 rotates counterclockwise about is pivot 99.

The pivoting of operating arm 82, aided by the tension spring 83 and breaker contact compression springs 86 and 87, causes the upper end of operating arm 82 to move clockwise to aid insulating arm 101, which is attached to contact arm 22 and draws contact arm 22 out of contact with nger contact 21. Breaking the engagement of contact arm 22 and finger contact 21 transfers the current flow to arcing contacts 27 and 28, which open after inger contact 21 and contact arm 22 separate. The arc drawn in the opening of arcing contacts 27 and 28 travels upward toward an arc chute 103 defined by barrier plates 104. The are terminals leave arcing contacts 27 and 28 and travel along an arc runner 29 and a contact extension 106, respectively. Arc chute 103, the barrier plates 104, and the effect of the magnetic iron core 107 arranged adjacent the underside of arc runner 29 combine with the thermal and magnetic conditions caused 4by the arc to aid in rapidly extinguishing the arc to interrupt the current in the power circuit controlled.

Figs. 2, 3 and 4 show the new and improved cover interlock assembly in detail. Fig. 2 shows the interlock assembly mounted in a circuit `breaker structure similar to that shown in Fig. 1. The cover 53 is shown in place, with the interlock arm 52 in its lowered position and the handle 54 of arm 52 extending through slot 56 in cover 53. A portion of cover 53 has been broken away to show detail. First and second trip blocks 41 and 43 mounted on shaft 42, star wheel 73, and one arm 77 of the rocker are shown.

As shown in Figs. 2 and 3, mounted on the inside of cover 53 is cover pin 55. When cover 53 is in place and arm 52 in its lowered position, cover pin 55 lies adjacent the lower part of prop lever 61. Prop lever 61 is pivotally attached to arm 52 at pivot 62. Prop lever 61 is delimited in its pivotal movement by limit pins 64 and 65, and partially delimited in its pivotal movement by cover pin 55 when cover 53 is in place.

In Fig. 2, pins 50, 66 and 67 are in toggle relation. Spring 63 is mounted between pins 66 and 67, and acts to hold interlock arm 52 down. When interlock arm 52 is raised to allow cover 53 to be removed, this toggle relation is broken and the tension spring 63 biases prop lever 61 into a substantially vertical position, thereby supporting interlock arm 52. Raising interlock arm 52 biases screw stop 58 against trip block 41, rotating trip block 41 in a clockwise direction. With the cover 53 '4 in place, and cover pin 55 limiting the movement of prop lever 61, a downward push on handle 54 of arm 52 will restore the toggle relation of pins 50, 66 and 67, and permit the closing of the circuit breaker mechanism.

For test purposes prop lever 61, even while cover 53 is removed, may be rotated clockwise and interlock arm 52 manually depressed and held down. When interlock arm 52 is released, spring 63 again operates to bias prop lever 61 into position to support interlock arm 52 in a raised position and thereby hold the circuit breaker contacts open.

Fig. 4 is a top plan view of the cover interlock assembly in the same position shown in Fig. 2. Fig. 4 shows bracket 20 attached to back panel 11, arrn 52 pivotally attached to bracket 51 at pivot point 50, and tension spring 63 attached to pins 66 and 67. Fig. 4 also illustrates the way in which handle 54 of arm 52 may be padlocked to bracket 60, to prevent removal or opening of cover 53 by unauthorized personnel.

It will be thus be seen that there has been provided in this invention a new and improved cover interlock assembly in which the objects above set forth, together with many practical advantages, are achieved. The construction is automatic in operation, and because of its uncomplicated construction can be adapted to a wide variety of industrial equipment.

Although only one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modification may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

What is claimed is:

1. In a circuit interrupting device, the combination comprising, a frame structure, a control element mounted on said frame and adapted for movement between a circuit closed position and a circuit open position, an enclosure for said control element including a removable cover, interlock means for selectively moving said control element to said circuit open and closed positions including an arm mounted on said frame for pivotal movement between a first position and a second position, said arm being engageable with said cover to hold said cover in a closed position to prevent said cover being removed while said arm is in said first position, means for transmitting to said control element the pivotal movement of said arm from said first arm position to said second arm position to move said control element from said circuit closed position to said circuit open position, and means connected to said arm and operable in response to movement of said arm from said iirst position to said second position to engage said frame structure and latch said arm in said second position and said control element in said circuit open position.

2. In a circuit interrupting device, the combination comprising, a frame structure, a control element mounted on said frame and adapted for movement between a circuit closed position and a circuit open position, an enclosure for said control element including a removable cover, interlock means for selectively moving said control element to said circuit open and closed positions including an arm mounted on said frame for pivotal movement between a first position and a second position, said arm being engageable with said cover to hold said cover in a closed position to prevent said cover being removed while said arm is in said tirst position, means for transmitting to said control element the pivotal movement of said arm from said first arm position to said second arm position to move said control element from said circuit closed position to said circuit open position, latch means connected to said arm and operable in response to movement of said arm from said first position to said second position to engage said frame structure and latch said arm in said second position and said control element in said circuit open position, and means connected to said cover operable to delimit operation .of said latch means whlle said cover `is in said closed position.

3. In a circuit interrupting device, the combination comprising, a 'frameistmcture a control element mounted on said frame and adapted for movement between a circuit 4'closed position and a `circuit open position, an enclosure for said control element including a removable .covering having an aperture, interlock means for selec- 'tively moving said control element to said circuit o pen .and closed positions including an arm mounted on said 'frame 'for pivotal movement between a iirst position and a .second position, a handle mounted on said arm, said handle extending 'through said aperture and engaging with said cover to hold said cover in a `closed position ,to prevent said cover being removed while said arm 1s in Vsaid lirst position, means for transmitting to said control element the pivotal movement of said arm from said 'first arm position to said second arm position to move said control element from said circuit closed position to said circuit open position, and means connected to said .arm `and operable in response yto movement of said arm from said lirst position to said second position to engage said frame structure and latch said arm in said second position .and said control element in said circuit open position.

4. In a circuit interrupting device, Jthe combination comprising, yaiframe structure, a .control element mounted on said frame and adapted for movement between a circuit closed position and a circuit open position, an enclosure for said control element including a removable cover, interlock means for selectively moving said control element to said circuit open and closed positions including an arm mounted on said frame for pivotal movement between a iirst position and a second position, said arm being engageable with said cover to hold said cover in a closed position to prevent said cover being removed while said arm is in said rst position, means for transmitting to said control element the pivotal movement of said arm from said rst arm position to said second arm position to move said control element from said circuit closed position to said circuit open position, and latch means operable in response to movement of said arm from said iirst position to said second position to engage said frame structure and latch said arm in said second position and said control element in said circuit open position, said latch means including a prop lever pivotally attached to said arm and a tension spring secured between said prop lever and said frame structure and a support mounted on said frame on which said prop lever rests when said arm is in said second position.

5. In a circuit interrupting device, the combination comprising, a frame structure, a control element mounted on said frame and adapted for movement between a circuit closed position and a circuit open position, an enclosure for said control element including a removable cover, interlock means for selectively moving said control element to said circuit open and closed positions including an arm mounted on said frame for pivotal movement between a first position and a second position, said arm being engageable with said cover to hold said cover in a closed position to prevent said cover being removed while said arm is in said irst position, means for transmitting to said control element the pivotal movement of said arm from said first arm position to said second arm position to move said control element. from said circuit closed position to said circuit open position, and latch means operable in response to movement of said arm from said iirst position to said second position to engage said frame structure and latch said arm in said second position and said control element in said circuit open position, said latch means including a prop lever pivotally attached to said arm and a tension spring secured between said prop lever and said frame structure, a support mounted on said frame on which said prop lever rests Awhen said arm is in said second position, and lmeans connected to said cover operable to 'delimit operation of said latch means 'while said cover is in said closed position.

l6. In a circuit `interrupting device, the combination comprising, a frame structure, a control element mounted on said *frame and adapted for movement .between a circuit closed :position and a circuit open position, an enclosure for said control element including a removable cover, interlock means for selectively moving said control 'element to said circuit open and closed positions including an arm mounted at a 'first point on said frame for pivotal movement between a iirst position `and a lsecond position, `said arm being engageable with said cover `to hold said cover in a closed position to prevent said cover being removed While said arm is in said 'iirst position, means for .transmitting to said cont-rol element vthe -pivotal movement of said arm from said first arm position to said second arm position to move said control element from Asaid circuit closed position to said circuit -open position, and 'latch lmeans operable in response Vto movement of said arm from Ysaid liirst position `to said 'second :position to Aengage vsaid frame structure and latch said arm lin-saidsecond position and said 'control element in -said :circuit -open position, said *latch ymeans including :a prop lever pivotally attached to `said arm and va tenl.sion sprin'g'secmted :between 'a second point on said prop lever and a third point on said frame structure, said rst, second and third points being in toggle relation, a support mounted on said frame on which said prop lever rests when said arm is in said second position, and pin means connected to said cover operable to limitoperation of said prop lever while said cover is in said closed position, thereby allowing said toggle relation between said tirst, second and third points to be reestablished.

7. In a circuit interrupting device, the combination comprising, a frame structure, a control element mounted on said frame and adapted for movement between a circuit closed position and a circuit open position, an enclosure for said control element including a removable cover, interlock means for selectively moving said control element to said circuit open and closed positions including an arm mounted at a lirst point on said frame for pivotal movement between a iirst position and a second position, said arm being engageable with said cover to hold said cover in a closed position to prevent said cover being removed while said arm is in said first position, means for transmitting to said control element the pivotal movement of said arm from said lirst arm position to said second arm position to move said control element from said circuit closed position to said circuit open position, and latch means -operable in response to movement of said arm from said iirst position to said second position to engage said frame structure and latch said arm in said lsecond position and said control element in said circuit open position, said latch means including a prop lever livotally attached to said arm and a tension spring secured between a second point on said prop lever and a third point on said frame structure, said first, second and third points being in toggle relation, a support mounted on said frame on which said prop lever rests when said arm is in said second position, and pin means connected to said cover operable to limit operation of said prop level while said cover is in said closed position, said pin means operable upon removal of said cover to allow full operation of said prop lever to lock said arm in second position.

8. In a circuit interrupting device, the combination comprising, a frame structure, a control element mounted on said frame and adapted for movement between a circuit closed position and a circuit `open position, an enclosure for said control element including a removable cover having an aperture, interlock means for selectively moving said control element to said circuit open and U closed positions including an arm mounted on said frame for pivotal movement between a first position and a second position, a handle mounted on said arm, said handle extending through said aperture and engaging with said cover to hold said cover in a closed position to prevent said cover being removed while said arm is in said rst position, means for transmitting to said control element the pivotal movement of said arm from said first arm position to Lsaid second arm position to move said control element from said circuit closed position to said circuit open position, and latch means connected to said arm and operable in response to movement of said arm from said rst position to said second position to engage said frame structure and latch said arm in said second position and said control element in said circuit open position, Said latch means including a prop lever pivotally attached to said arm and a tension spring secured between said prop lever and said frame and a support mounted on said frame on which said prop lever rests.

9. In a circuit interrupting device, the combination comprising, a frame structure, a control element mounted on said frame and adapted for movement between a circuit closed position and a circuit open position, an enclosure for said control element including a removable cover having an aperture, interlock means for selectively moving said control element to said circuit open and closed positions including an arm mounted on said frame for pivotal movement between a rst position and a second position, a handle mounted on said arm, said handle extending through said aperture and engaging with said Cover to hold said cover in a closed position to prevent said cover being removed while said arm is in said rst position, means for transmitting to said control element the pivotal movement of said arm from said first arm position to said second arm position to move said control element from said circuit closed position to said circuit open position, means connected to said cover operable to disengage the latter said means while said cover is in said closed position, and latch means operable in response to movement of said arm from said first position to said second position to engage said frame structure and latch said arm in said second position and said control element in said circuit open position, said latch means including a prop lever pivotally attached to said arm, a tension spring secured between said prop lever and said frame and a support mounted on said frame on which said prop lever rests.

References Cited in the iile of this patent UNITED STATES PATENTS 2,449,820 Seaman Sept. 21, 1948 2,595,102 Santangelo Apr. 29, 1952 2,669,624 Ferguson Feb. 16, 1954 2,698,361 Mekelburg Dec. 28, 1954 

